The present invention generally relates to the field of materials characterization. In particular, the invention relates to high throughput screens for evaluating mechanical or physical properties of libraries of polymers or other materials.
Currently, there is substantial research activity directed toward the discovery and optimization of polymeric materials for a wide range of applications. Although the chemistry of many polymers and polymerization reactions has been extensively studied, nonetheless, it is rarely possible to predict a priori the physical or chemical properties a particular polymeric material will possess or the precise composition and architecture that will result from any particular synthesis scheme. Thus, characterization techniques to determine such properties are an essential part of the discovery process.
Combinatorial chemistry refers generally to methods for synthesizing a collection of chemically diverse materials and to methods for rapidly testing or screening this collection of materials for desirable performance characteristics and properties. Combinatorial chemistry approaches have greatly improved the efficiency of discovery of useful materials. For example, material scientists have developed and applied combinatorial chemistry approaches to discover a variety of novel materials, including for example, high temperature superconductors, magnetoresistors, phosphors and catalysts. See, for example, U.S. Pat. No. 5,776,359 (Schultz, et al). In comparison to traditional materials science research, combinatorial materials research can effectively evaluate much larger numbers of diverse compounds in a much shorter period of time. Although such high-throughput synthesis and screening methodologies are conceptually promising, substantial technical challenges exist for application thereof to specific research and commercial goals.
The characterization of polymers or other materials using combinatorial methods has only recently become known. Examples of such technology are disclosed, for example, in commonly owned U.S. Pat. Nos. 6,182,499 (McFarland, et al); 6,175,409 B1 (Nielsen, et al); 6,157,449 (Hajduk); 6,151,123 (Nielsen); 6,034,775 (McFarland, et al); 5,959,297 (Weinberg, et al), all of which are hereby expressly incorporated by reference herein.
Of particular interest to the present invention are combinatorial methods and apparatuses for screening polymers and other materials for physical or mechanical characteristics. Screening of the materials for mechanical properties presents a multitude of challenges. As an example, conventional instruments, such as conventional stress or strain testing machines and other apparatuses traditionally lack the ability to screen mechanical properties of several materials in rapid succession, in parallel, on a single substrate or a combination thereof. Thus, challenges are presented for forming systems that can quickly process and test (either in parallel or in serial succession) mechanical properties of many materials.
The present invention provides instruments and methods for screening combinatorial libraries that addresses many of the problems encountered when using conventional instruments. For example, the disclosed instruments can measure mechanical properties of library members in rapid serial or parallel test format, and can perform tests on small amounts of material, which are easily prepared or dispensed using art-disclosed liquid or solid handling techniques. Compared to conventional instruments, the disclosed instruments afford faster sample loading and unloading, for example, through the use of disposable libraries of material samples.
Thus, one aspect of the present invention provides instruments for measuring mechanical properties of a combinatorial library of materials. The instruments include at least one mounting member to which the library of material samples is removably secured for testing; at least one source selected from the group consisting of a fluid, a voltage, a piezoelectric and a combination thereof for delivering one or more forces to each library member; and at least one sensing device for monitoring the response each library member to the one or more forces.
Another aspect of the present invention provides methods of screening a combinatorial library of materials. In a preferred embodiment, the methods include providing a combinatorial library of materials comprising at least four different samples, and delivering one or more forces to at least two of the samples simultaneously by a source selected from the group consisting of a fluid, a voltage, a piezoelectric and a combination thereof. The methods further include monitoring the response of each library member to the one or more forces. In another preferred embodiment, the method includes providing a combinatorial library of materials having at least four different samples; delivering one or more force to each of the samples serially by a source selected from the group consisting of a fluid, a voltage, a piezoelectric and a combination thereof; and monitoring the response of each library member to the one or more forces at a throughput rate no greater than about 10 minutes per sample. Depending on the type of force applied, the methods can screen libraries of materials for a variety of mechanical properties related to Young""s modulus (e.g., flexure, uniaxial extension, biaxial compression, and shear), failure (stress and strain at failure, toughness), adhesion, or others.